Heterocyclic-alkylene quinoxalinyloxyphenoxypropanoate herbicides

ABSTRACT

Heterocyclic-alkylene guinoxalinyloxyphenoxypropanoate compounds exhibit unexpectedly desirable selective herbicidal activity. Also disclosed are compositions comprising such compounds as well as a method of controlling the growth of undesirable plants employing such compounds.

This application is a division of U.S. patent application Ser. No.07/876,614 filed Apr. 30, 1992 now U.S. Pat. No. 5,319,102, which is acontinuation of U.S. patent application Ser. No. 07/378,357 filed Jul.11, 1989, now U.S. Pat. No. 5,120,348, which is a continuation-in-partof U.S. patent application Ser. No. 07/141,182 filed Jan. 6, 1988, nowabandoned.

FIELD OF THE INVENTION

This invention is directed to novel heterocyclicalkyleneguinoxalinyloxyphenoxypropanoate compounds which exhibit unexpectedlydesirable selective herbicidal activity. In other aspects, thisinvention is directed to herbicidal compositions comprising suchcompounds as well as to a method for controlling the growth of plantsemploying such quinoxalinyl derivatives.

BACKGROUND OF THE INVENTION

The control of undesirable grasses is important in the cultivation ofmany important broadleaf agricultural species such as soybeans, peanutsand cotton, as well as in the cultivation of many horticultural species.Moreover, the presence of such weeds on noncropped areas may present afire hazard, or may result in the undesirable drifting of sand or snowor irritation to persons with allergies. Accordingly, it would bebeneficial to control the growth of undesirable grasses, particularly ina manner which would allow for the selective control of such plantswithout concurrent injury to desirable broadleaf crops or vegetation.

Among the classes of compounds which have been employed in the past tocontrol the growth of undesirable vegetation are certainquinoxalinyloxyphenoxy compounds. Thus, Ura et al in U.S. Pat. No.4,629,493 disclose certain quinoxalinyl compounds, including 6-memberedhomocyclic ring derivatives such as benzyl2-[4-(6-chloro-2-guinoxalinyloxy)phenoxy]-propanoate, which are usefulas selective herbicides. Similarly, in European Patent Application46,467, Ura et al show a number of guinoxalinyloxyphenoxy compounds,including a morpholino ester thereof, which are useful as herbicides.

Somewhat similarly, U.S. Pat. No. 4,429,167 to Lee discloses a broadrange of 3-alkoxy-4-substituted-phenoxy-2,-3-unsaturated acids,including quinoxalinyl derivatives thereof which are selectiveherbicides for grasses, while U.S. Pat. No. 4,609,396 to Fawzi shows avariety of guinoxalinyloxy ethers which are useful for controlling grassweeds in broadleaf plants. Chemical Abstracts 98, 198278m (1983)discloses herbicidal glycidyl guinoxalin-2-yloxyphenoxypropionates whileEuropean Patent Application 206,772 shows quinoxalinyloxybenzyl estercompounds which are useful for the selective control of weeds in rice.Spanish Patent Application 8,603,431 shows herbicidal alkylquinoxalinyloryphenoxypropanoates while European Patent Application113,831 Shows selective herbicides which are carbamylethyl esters ofquinoxalinyloxyphenoxypropanoic scis. European Patent Application121,871 shows herbicidal phosphoric acid esters ofquinoxalinyloxyphenoxypropanoates while U.S. Pat. No. 4,499,271 showsphosphoric acid esters of quinoxalinyloxyphenoxypropanoates. GermanApplication 3,433,390 shows silane esters ofquinoxalinyloxyphenoxypropanoic acid, while Kruger et al in U.S. Pat.No. 4,601,748 disclose herbicidal 2-phenoxypropionic acid derivatives ofpentitols.

In contrast, U.S. Pat. No. 4,564,381 to Bieringer et al shows a verybroad class of compounds, including many quinoxalinyloxyphenoxypropanoicesters which function as plant growth stimulants.

While many of the compounds shown in the above publications exhibitdesirable herbicidal activity, it would nevertheless be desirable topossess herbicides which exhibited enhanced selective control ofundesirable grasses.

Acccordingly, it is an object of this invention to provide a class ofnovel compounds which exhibit unexpectedly desirable selectiveherbicidal activity.

It is a further object of this invention to provide a method ofcontrolling undesirable weeds.

These objects and other additional objects will become more fullyapparent from the following disclosure and accompanying examples.

DESCRIPTION OF THE INVENTION

In one aspect, this invention is directed to a novel class of compoundshaving the structural formula: ##STR1## wherein: n is 0, 1, 2 or 3;

R¹ and R² are each independently selected from the group consisting ofhalogen, hydrogen, C₁ -C₃ alkoxy, C₁ -C₃ haloalkoxy, monohalomethyl,dihalomethyl, trihalomethyl, cyanato and nitro; and

R³ is a 4-, 5- or 6-membered saturated, unsaturated or partiallyunsaturated heterocyclic zing containing 1 or 2 oxygen atoms, or a 5- or6-membered saturated, unsaturated or partially unsaturated heterocyclicring containing 1 or 2 sulfur atoms or one sulfur atom mn one oxygenatom; said ring optionally being substituted with between 1 and 3substituents each independently selected from the group consisting ofoxo, C₁ -C₃ alkyl anti C₁ -C₃ alkoxy.

In another aspect, this invention is directed to a herbicidalcomposition comprised of:

(A) a compound having the structural formula: ##STR2## wherein: n is 0,1, 2 or 3;

R¹ and R² are each independently selected from the group consisting ofhalogen, hydrogen, C₁ -C₃ alkoxy, C₁ -C₃ haloalkoxy, monohalomethyl,dihalomethyl, trihalomethyl, cyanato and nitro; and

R³ is a 4-, 5- or 6-membered saturated, unsaturated or partiallyunsaturated heterocyclic ring containing 1 or 2 oxygen atoms, or a 5- or6-membered saturated, unsaturated or partially unsaturated heterocyclicring containing 1 or 2 sulfur atoms or one sulfur atom and one oxygenatom; said ring optionally being substituted with between 1 and 3substituents each independently selected from the group consisting ofoxo, C₁ -C₃ alkyl and C₁ -C₃ alkoxy, and

(B) a suitable carrier.

In yet another aspect, this invention is directed to a method ofcontrolling undesirable plants, which method comprises applying to thelocus of such undesirable plants a herbicidally effective amount of acompound having the structural formula: ##STR3## wherein: n is 0, 1, 2or 3;

R¹ and R² are each independently selected from the group consisting ofhalogen, hydrogen, C₁ -C₃ alkoxy, C₁ -C₃ haloalkoxy, monohalomethyl,dihalomethyl, trihalomethyl, cyanato and nitro; and

R³ is a 4-, 5- or 6-membered saturated, unsaturated, or partiallyunsaturated heterocyclic ring containing 1 or 2 oxygen atoms, or a 5- or6-membered saturated, unsaturated or partially unsaturated heterocyclicring containing 1 or 2 sulfur atoms or one sulfur atom and one oxygenatom; said ring optionally being substituted with between 1 and 3substituents each independently selected from the group consisting ofoxo, C₁ -C₃ alkyl and C₁ -C₃ alkoxy. The novel compounds of thisinvention are of the formula: ##STR4## wherein R¹, R², R³ and n are asdefined for formula (I) above. It is to be noted that R³ may be anunsaturated, saturated or partially unsaturated (i.e., containing atleast one carbon-carbon double bond and at least one carbon-carbonsingle bond) heterocyclic moiety.

Preferably:

R¹ is chlorine, trichloromethyl or trifluoromethyl;

R² is hydrogen; and

R³ is furanyl, tetrahydrofuranyl, dioxolanyl, tetrahydrodioxolanyl,dihydropyranyl, tetrahydropyranyl, tetrahydrothiophenyl,tetrahydrothiophenyl-1,1-dioxide, tetrahydrothiopyranyl,(thiophenyl)methyl, (thiophenyl)ethyl, (dimethyloxathiophenyl)methyl,(dimethyldithiolanyl)methyl or thiochromanyl; optionally substitutedwith 1, 2 or 3 moleties selected from the group consisting of oxo andmethyl. Particularly preferred compounds include:

2-tetrahydrofuranylmethyl2-[4-(6-chloro-2-quinoxalinyloxy)phenoxy]-propanoate;

2-fursnylmethyl 2-[4-(6-chloro-2-quinoxalinyloxy)-phenoxy]propanoate;

2-tetrahydropyranylmethyl2-[4-(6-chloro-2-quinoxalinyloxy)-phenoxy]-propanoate;

2-[2-(2-methyl-1,3-dioxolanyl)]ethyl2-[4-(6-chloro-2-quinoxalinyloxy)phenoxy]propanoate;

4-(2,2-dimethyl-1,3-dioxolanyl)methyl2-[4-(6-chloro-2-quinoxslinyloxy)phenoxy]propanoate;

3-tetrahydrothiophenyl2-[4-(6-chloro-2-quinoxalinyloxy)phenoxy]propanoste;

4-tetrahydrothiopyranyl2-[4-(6-chloro-2-guinoxalinyloxy)phenoxy]propanoste;

3-tetrahydrothiopyranyl2-[4-(6-chloro-2-quinoxalinyl-oxy)phenoxy]propanoate;

3-tetrahydrothiophenyl-1,1-dioxide2-[4-(6-chloro-2-quinoxalinyloxy)phenoxy]propanoate;

2-thiophenylmethyl 2-[4-(6-chloro-2-guinoxalinyloxy)phenoxy]propanoate;

2-(2-thiophenyl)ethyl2-[4-(6-chloro-2-quinoxalinyloxy)-phenoxy]propanoate;

5-(2,2-dimethyl-1,3-oxathiolanyl)methyl2-[4-(6-chloro-2-quinoxalinyloxy)phenoxy]propanoate;

4-(2,2-dimethyl-1,3-dithiolanyl)methyl2-[4-(6-chloro-2-quinoxalinyloxy)phenoxy]propanoate; and

4-thiochromanyl 2-[4-(6-chloro-2-quinoxalinyloxy)phenoxy]propanoate.

The compounds of this invention may be prepared by reacting aguinoxalinyloxyphenol compound of the formula: ##STR5## wherein R¹ andR² are as defined for structure (I) above; with a substitutedheterocyclicalkylpropanoate of the formula: ##STR6## wherein X ishalogen, mesylate or rosylate and n and R³ are as defined for structure(I) above. This reaction is typically conducted in an organic solvent(such as dimethylformamide, dimethylsulfoxide, acetonitrile or the like)in the presence of an inorganic or organic base (such as sodiumcarbonate, potassium hydroxide or potassium carbonate) at suitabletemperature.

The guinoxalinyloxyphenoxy starting materials may be prepared byreacting a 2-haloquinoxaline compound having the formula: ##STR7##wherein X is halogen and R¹ and R² are as defined in structure (I)above, with a phenyl benzyl ether of the formula: ##STR8## in thepresence of an inorganic or organic base to produce an intermediate ofthe formula: ##STR9## and hydrogenating such intermediate (employing ahydrogenation catalyst such as palladium) to produce a debenzylationthereby forming the quinoxalinyloxyphenol starting material.

The heterocyclicalkylpropanoate starting material may be produced byreacting a halogenated propionic acid halide with the appropriateheterocyclic alkyl alcohol.

Alternatively ethyl 2-halopropanoate may be reacted with the appropriateheterocyclic alkyl alcohol in the presence of an appropriate catalyst(such as tetra-isopropoxy titanium) to produce theheterocyclicalkylpropanoate halide via a tzansesterification process.

The compositions of this invention are comprised of (A) at least one ofthe guinoxalinyloxyphenoxypropanoate compounds of this invention, and(B) a suitable carrier.

To prepare such herbicidal compositions, thequinoxalinyloxyphenoxypropanoate compound may be mixed with inertingredients to provide compositions in the form of finely-dividedparticulate solids, granules, pellets, wettable powders, flowableliquids, soluble powders, solutions, and aqueous or organic solventdispersions or emulsions. Such formulations may be of several differentphysical and chemical types, any of which could be made by one familiarwith the art. For instance, the active compound may be impregnated onfinely-divided or granular inorganic or organic carriers such asattapulgite clay, sand, vermiculite, corn cob, activated carbon or othergranular carriers known to the art. The impregnated granules may then bespread on the soil or incorporated into the soil.

Alternatively, the chemical may be formulated as a wettable powder bymixing it with an inactive powdered carrier to which a surface activedispersing agent has been added and grinding the mixture into a finepowder. Typical powdered solid carriers are the various mineralsilicates (such as mica, talc, pyrophyllite, clays and the like) orpowdered organic material (e.g., corn cob). The wettable powder may thenbe dispersed in water and sprayed on the soil surface, or on crop orweed plants.

Similarly, an emulsifiable concentrate may be prepared by dissolving thechemical in a solvent such as xylene, toluene, or other aliphatic oraromatic hydrocarbon to which a surface active dispersing agentgenerally has been added. The emulsifiable concentrate may then bedispersed in water and applied by spraying.

The concentration of sctive chemical in the composition may vary widelytypically ranging from about I to about 95% by weight. The concentrationof active chemical in dispersions applied to the soil, seed or foliageis typically between about 0.002% and about 80% by weight.

Formulations containing the active ingredient(s) may be dispersed inwater or an organic liquid (such as oil) and applied to target plants.Surface active agents may be added to the applied solution to increaseits qualitative or quantitive range of activity. Suitable surface activeagents are well known to those skilled in the art. Reference may be madeto McCutcheon's Detergents and Emulsifiers (1980, Allured Publ. Co.,Ridgewood, N.J.) for examples of appropriate surface active agents.Suitable adjuvants containing appropriate surface active agents include"AGRI-DEX" and "INDUCE" (Helena Chemical Co.), "SUPER SAVOL"(Leffingwell), "CANPLUS 411" (Atlas), and "ASSIST" (BASF). Similarly,such formulations may be applied to the soil either as a liquid or agranule.

For use as a preemergence herbicide the compound of this invention istypically applied at a rate of from about 0.01 to about 10 pounds peracre (about 0.01 to about 11.2 kg/ha) to soil which contains weed andcrop seed. Such application is made either to the surface of the soil orinto the upper one to three inches (2.5 to 7.5 cm.) of soil. Whenemployed as a postemergence herbicide the compound is typically appliedat a rate of from about 0.01 to about 10 pounds per acre (about 0.01 toabout 11.2 kg/ha) to the aerial portions of weeds.

The most suitable dosage of application, and the most effective type endamount of adjuvant substance will depend on a number of factors,including the plant species; the stage of plant development; the methodof application; the air and soil temperature and the quantity andintensity of rainfall before and after treatment; the soil type, pH,fertility and moisture and organic matter content; the physiologicalcondition and vigor of the target plants; the relative humidity and windvelocity of the air around the crop at the time of treatment; the extentand density of the foliar canopy of the target plant; the light quality,intensity and duration each day; the type and interval of previous andsubsequent crop protectant chemical applications. However, one skilledin the art can, by routine experimentation, readily determine optimumconditions for the employment of any particularquinoxyalinyloxyphenoxypropanoate compound.

The compounds of the present invention include the isomeric forms andmixtures thereof. Thus, the invention includes the optically activeisomers and racemic mixtures. Unless otherwise specified herein, thecompounds described in the examples are racemic mixtures.

EXAMPLES

The following Examples are intended to further illustrate the inventionand are not intended to limit the scope of the invention in any mannerwhatsoever.

Example 1 Preparation of 2-tetrahydrofuranylmethyl2-[4-(6-chloro-2-guinoxalinyloxy)phenoxy]propanoate (Compound Number 4)A. Preparation of 2-tetrahydrofuranylmethyl 2-bromopropanoate

To a 250 milliliter three-necked flask were added 0.15 mole of2-(hydroxymethyl)tetrahydrofuran, 0.15 mole of triethylamine, and 100milliliters of diethylether. The flask was immersed in ice, and 0.15mole of 2-bromopropanoyl chloride introduced dropwise. The ice bath wasremoved, and the reaction stirred at ambient temperature for two hours.The mixture was extracted with an equal volume of water, and the organicphase dried over sodium sulfate. Pecanration and solvent removalresulted in 2-tetrahydrofuranylmethyl 2-bromopropanoate in 94% yield.

B. Preparation of 2-tetrahydrofuranylmethyl2-[4-(6-chloro-2-quinoxalinyloxy)-phenozy]propanoate

To a 500 milliliter roundbottom flask were added 0.055 mole of2-(4-hydroxyphenoxy)-6-chloroquinoxaline, 0.055 mole of2-tetrahydrofuranylmethyl 2-bromopropanoate, 0.110 mole of anhydrouspotassium carbonate, and 250 milliliters of acetonitrile. The mixturewas refluxed for 5.5 hours and the solvent removed. The residue wasfiltered through a column of alumina with dichloromethane. Solventremoval and recrystallization from boiling hexane resulted in an 85%yield of 2-tetrahydrofuranylmethyl2-[4-(6-chloro-2-guinoxalinyloxy)phenoxy]propanoate. The material meltedover a range of 52°-55° C.

Example 2 Preparation of 2-thiophenylmethyl2-[4-(6-chloro-2-quinoxalinyloxy)phenoxy]propanoate (Compound Number 11)A. Preparation of 2-thiophenylmethyl 2-bromopropanoate

To a 50 milliliter three-necked flask equipped with stir bar, glassstopper, rubber stopple, connecting tube, and nitrogen atmosphere wereadded 2.1808 grams (0.0191 moles) of 2-hydroxymethylthiophene, 2.66milliliters (0.0191 moles of triethylamine, and 20 milliliters ofanhydrous diethylether.

The flask was immersed in an ice water bath, and 2.0 milliliters (0.0191moles) of 2-bromopropanoyl bromide added dropwise by syringe. Themixture was stirred at 0° for 5 minutes, then at ambient temperature forone hour. Triethylamine hydrochloride was removed by filtration on aBuchner funnel and with two water extractions of the organic phase.Drying of the ether solution over anhydrous sodium sulfate, decantation,and solvent removal by rotary evaporation resulted in a quantitativeyield of 2-thiophenylmethyl 2-bromopropanoate as an oil.

B. Preparation of 2-thiophenylmethyl2-[4-(6-chloro-2-guinoxalinyloxy)phenoxyl]propanoate

To a 250 milliliter roundbottom flask equipped with stir bar, refluxcondenser, connecting tube, and nitrogen atmosphere were added 4.3781grams (0.0161 moles) of 2-(4-hydroxyphenoxy)-6-chloroquinoxaline, 4.000grams (0.0161 moles) of 2-thiophenylmethyl 2-bromopropanoate, 4.4377grams (0.0321 moles) of anhydrous potassium carbonate, and 100 millitersof acetonitrile.

The mixture was refluxed for 6 hours, then filtered while hot through aMuchnet funnel. Acetonitrile was removed by rotary evaporation, and theresidue plug filtered through a column of alumina with dichloromethane.Solvent removal at reduced pressure resulted in 4.6389 grams of tansolid 2-thiophenylmethyl2-[4-(6-chloro-2-quinoxalinyloxy)phenoxy]-propanoate, a 65.3% yield.

Example 3

Additional compounds within the scope of the invention were preparedusing essentially the procedures outlined above. The structures andmelting points are summarized in Table I below. The NMR spectra ofcompounds 3, 5 and 7-18 are summarized in Table II below. (Note: in suchNMR data s=singlet; d=duplet; t=triplet; q=quartet; and m=multipier).

                  TABLE 1                                                         ______________________________________                                         ##STR10##                                                                    Compound                               Melting                                Number  R.sup.1 R.sup.2                                                                             R.sup.3      n   Point (°C.)                     ______________________________________                                         1      6-Cl    H                                                                                    ##STR11##   1   130-134°                         2      6-Cl    H                                                                                    ##STR12##   1    98-101°                         3      6-Cl    H                                                                                    ##STR13##   1   Oil                                     4      6-Cl    H                                                                                    ##STR14##   1   52-55°                           5      6-Cl    H                                                                                    ##STR15##   2   Oil                                     6      6-Cl    H                                                                                    ##STR16##   1   60-64°                           7      6-Cl    H                                                                                    ##STR17##   0   78-82°                           8      6-Cl    H                                                                                    ##STR18##   0   Oil                                     9      6-Cl    H                                                                                    ##STR19##   1   Oil                                    10      6-Cl    H                                                                                    ##STR20##   0   Oil                                    11      6-Cl    H                                                                                    ##STR21##   0   Oil                                    12      6-Cl    H                                                                                    ##STR22##   0   Oil                                    13      6-Cl    H                                                                                    ##STR23##   1   Oil                                    14      6-Cl    H                                                                                    ##STR24##   1   112-114°                        15      6-Cl    H                                                                                    ##STR25##   2   171-172°                        16      6-Cl    H                                                                                    ##STR26##   1   Oil                                    17      6-Cl    H                                                                                    ##STR27##   1   Oil                                    18      6-Cl    H                                                                                    ##STR28##   0   Oil                                    ______________________________________                                    

                  TABLE II                                                        ______________________________________                                        Nuclear Magnetic Resonance Data                                               Compound                                                                      Number  NMR(CDCl.sub.3)                                                       ______________________________________                                         3      1.38(s, 3H), 1.43(s, 3H), 1.68(d, 3H),                                        3.50-4.24(m, 5H), 4.80(q, 1H), 7.02(q, 4H),                                   7.59(s, 2H), 8.00(s, 1H), 8.61(s, 1H).                                 5      1.46(s, 3H), 1.77(d, 3H), 2.14(t, 2H), 3.99(s, 4H),                           4.38(t, 2H), 4.81(q, 1H), 7.07(q, 4H), 7.62(s, 2H),                           8.02(s, 1H), 8.62(s, 1H).                                              8      1.64(d, 3H), 3.70-3.96(m, 5H), 4.78(q, 1H),                                   5.38(s, 1H),                                                                  6.92-7.20(q, 4H), 7.54-7.68(m, 2m),                                           8.02(s, 1H),                                                                  8.65(s, 1H).                                                           9      1.21(s, 3H), 1.60(d, 3H), 4.08-4.48(m, 6H), 4.78(q,                           1H), 6.76-7.18(q, 4H), 7.48(m, 2H), 7.88(s, 1H),                              8.52(s, 1H).                                                          10      1.63(d, 3H), 1.88-2.35(m, 2H), 2.73-3.18(m, 4H),                              4.79(q, 1H), 5.57(m, 1H), 6.96(d, 2H), 7.20(d, 2H),                           7.63(m, 2H), 8.03(s, 1H), 8.65(s, 1H).                                11      1 65(d, 3H), 1.70-2.19(m, 4H), 2.46-2.87(m, 4H),                              4.78(q, 1H), 4.95(m, 1H), 6.95(d, 2H), 7.08(d, 2H),                           7.63(m, 2H), 8.03(s, 1H), 8.67(s, 1H).                                12      1.65(d, 3H), 1.77-2.21(m, 4H), 2.45-2.82(m, 4H),                              4.77(q, 1H), 4.98(s, 1H), 6.96(d, 2H), 7.17(d, 2H),                           7.63(m, 2H), 8.04(s, 1H), 8.65(s, 1H).                                13      1.63(d, 2H), 2.47(m, 2H), 2.94-3.27(m, 4H), 4.85(q,                           1H), 5.59(m, 1H), 6.96(d, 2H), 7.22(d, 2H), 7.60(m,                           2H), 8.01(s, 1H), 8.65(s, 1H).                                        14      1.64(d, 3H), 4.75(q, 1H), 5.32(s, 2H), 6.73-7.37(m,                           7H), 7.55(m, 2H), 7.97(s, 1H), 8.57(s, 1H).                           15      1.69(d, 3H), 3.19(t, 2H), 4.42(t, 2H), 4.78(q, 1H),                           6.71-7.31(m, 7H), 7.52(m, 2H), 7.96(s, 1H), 8.58(s,                           1H).                                                                  16      1.61(d, 3H), 1.67(s, 6H), 2.98(m, 2H), 4.38(m, 3H),                           4.83(q, 1H), 6.96(d, 2H), 7.19(d, 2H), 7.62(m, 2H),                           8.02(s, 1H), 8.67(s, 1H).                                             17      1.57-1.82(m, 9H), 2.91-3.12(m, 2H), 4.11-4.39(m, 3H),                         4.80(q, 1H), 6.95(d, 2H), 7.18(d, 2H), 7.63(m, 2H),                           8.03(s, 1H), 8.66(s, 1H).                                             18      1.62(d, 3H), 4.77(q, 1H), 6.08(m, 1H), 6.87-7.18(m,                           4H), 6.91(d, 2H), 7.15(d, 2H), 7.61(m, 2H), 8.02(s,                           1H), 8.63(s, 1H).                                                     ______________________________________                                    

Example 4 Preemeruence Control

To illustrate the effectiveness of the heterocyclicalkylenequinoxalinyloxyphenoxypropanoate compounds of this invention aspreemergence herbicides, 300 mg of each of the below listed compoundswere dissolved in 10 ml acetone to which 30 mg of an emulsifying agent,ethoxylated sorbitan monolaurste, were added. The solution was dilutedto 100 ml with distilled water. Ten milliliters of this 3000 ppmsolution were diluted to 250 ppm with distilled water. The chemical wasapplied at the rate of 10 lb/A (11.2 kg/ha) by drenching 46 ml of the250 ppm solution on the surface of soil in 41/2 inch (11.25 cm.) plasticpots wherein seeds of the following weeds had been planted; velvet leaf(Abutilon theophrasti Medic.), "VL"; jimsonweed (Datura stramonium L.),"JW", or prickly sida (Sida spinosa L.), "PS"; tall morningglory (Ipomeapurpurea L. Roth), "TM"; switchgrass (Panicum viraatum L.), "BG";barnyard grass (Echinolchloa crus-aalli (L.) Beauv.), "BG"; and greenfoxtail (Setaria viridis) (L.) Beauv.), "GF".

The percent control of the weeds compared to untreated checks wasdetermined two weeks after treatment. The results of such testing aresummarized in Table III below.

                  TABLE III                                                       ______________________________________                                        Preemergent Control                                                           Compound                                                                              Percent Weed Control                                                  Number  VL      JW     PS    TM    BG   SG   GF                               ______________________________________                                         1      0       0      --    0     100  100  100                               2      0       0      --    0     100  100  100                               3      0       0      --    0     100  100  100                               4      0       0      --    0     100  100  100                               5      0       0      --    0     100  100  100                               6      0       0      --    0     100  100  100                               7      0       0      --    0     100  100  100                               8      0       0      --    0     100  100  100                               9      0       0      --    0     100  100  100                              10      0       --     0     0     100  100  100                              11      0       --     95    0     100  100  100                              12      0       --     0     0     100  100  100                              13      0       --     0     0     100  100  100                              14      60      50     --    75    100  100  100                              15      65      40     --    15    100  100  100                              16      0       --     100   0     --   100  100                              17      0       --     0     0     100  100  100                              18      0       --     100   50    100  100  100                              ______________________________________                                    

The above data show the excellent selective preemergent herbicidalcontrol exhibited by the compounds of this invention.

Example 5 Postemergence Control

To illustrate the effectiveness of the compounds of this invention aspostemergence herbicides, the 3000 ppm solutions described under Example4 were atomired with a conventional DeVilbiss [trademark] sprayer,wetting the foliage to the drip point. The remainder of the procedurewas the same as described under Example 4. The weeds, which were thesame species as described under Example 4, were treated six days afteremergence.

The percent weed control was evaluated two weeks after treatment. Theresults of such testing are summarized in Table IV below.

                  TABLE IV                                                        ______________________________________                                        Postemergence Treatment                                                       Compound                                                                              Percent Weed Control                                                  Number  VL       JW     PS   TM    BG   SG   GF                               ______________________________________                                         1      0        0      --    0    100  100  100                               2      0        0      --   15    100  100  100                               3      10       90     --   15    100  100  100                               4      0        20     --   10    100  100  100                               5      0        0      --   40    100  100  100                               6      0        20     --   10    100  100  100                               7      0        0      --    5    100  100  100                               8      0        0      --    5    100  100  100                               9      0        0      --    5    100  100  100                              10      30       --     0    50    100  100  100                              11      40       --     15   20    100  100  100                              12      0        --     0    10    100  100  100                              13      0        --     20   60    100  100  100                              14      15       30     --    0    100  100  100                              15      30       35     --   10    100  100  100                              16      100      --     65   40    100  100  100                              17      10       --     0     5    100  100  100                              18      0        --     0     0    100  100  100                              ______________________________________                                    

The above data show the desirable selective postemergent herbicidalcontrol exhibited by the novel compounds of this invention.

Example 6

To illustrate the effectiveness of the novel heterocyclicalkylenequinoxalinyloxyphenoxypropanoate derivatives of this invention forpreemergence grass control relative to prior art⁼ homocyclicalkyleneguinoxalinyloxy-phenoxypropanoate compounds, solutions of several of thecompounds were prepared in a manner similar to that described inExample 1. The 250 ppm solutions were diluted to 3.1 ppm with distilledwater to provide testing at a rate of 0.14 kg/ha as a 46 ml drench to11.25 cm diameter pots. In a similar manner, solutions of CompoundA--benzyl 2-[4-(6-chloro-2-guinoxalinyloxy)phenoxy]propanoate, acompound within the scope of U.S. Pat. No. 4,629,493 (Compound 55)--wereprepared and tested.

The structures of the tested compounds are as follows: ##STR29##

The results of such testing are summarized in Table V below.

                  TABLE V                                                         ______________________________________                                                       Percent Weed Control                                                      Rate    Wild      Green Barnyard                                   Compound   kg/ha   Oats      Foxtail                                                                             Grass                                      ______________________________________                                        2          0.14    60        80    60                                         4          0.14    70        80    80                                         6          0.14    50        70    90                                         A          0.14    50        65    30                                         ______________________________________                                    

The above data clearly show the unexpected desirable activity of thecompounds of the present invention relative to known homocyclic 5- or6-membered ring derivatives.

What is claimed is:
 1. A compound having the formula: ##STR30## wherein:n is 0, 1, 2 or 3;R¹ and R² are each independently selected from thegroup consisting of halogen, hydrogen, C₁ -C₃ alkoxy, C₁ -C₃ haloalkoxy,monohalomethyl, dihalomethyl, trihalomethyl, cyanato and nitro; and R³is a 4-, 5- or 6-membered saturated, unsaturated or partiallyunsaturated ring containing 1 or 2 oxygen atoms, or a 5- or 6-memberedsaturated, unsaturated or partially unsaturated heterocyclic ringcontaining 1 or 2 sulfur atoms or one sulfur atom and one oxygen atom;said ring having no nitrogen atoms and optionally being substituted withbetween 1 and 3 substituents each independently selected from the groupconsisting of oxo, C₁ -C₃ alkyl and C₁ -C₃ alkoxy; with the proviso thatwhen R¹ or R² is hydrogen or 6-chloro and n is 1, then R³ is either the5- or 6-membered saturated, unsaturated or partially unsaturated ringcontaining 1 or 2 oxygen atoms or the 5- or 6-membered saturated,unsaturated or partially unsaturated heterocyclic ring containing 1 or 2sulfur atoms or one sulfur atom and one oxygen atom, but not furanyl,tetrahydrofuranyl or tetrahydropyranyl.
 2. An herbicidal compositioncomprising:(A) an effective amount of a compound according to claim 1;and (B) a suitable carrier.
 3. A method for controlling the growth ofundesirable plants comprising:applying to the locus of such undesirableplants an herbicidally effective amount of a compound according toclaim
 1. 4. A method in accordance with claim 3 wherein said compound isapplied preemergently.
 5. A method in accordance with claim 3 whereinsaid compound is applied postemergently.